The invention relates to an anchoring mechanism for safety belts and more particularly it relates to such an anchoring mechanism for seat belts which surround a longitudinally and vertically adjustable motor vehicle seat supported on the body of the vehicle. The anchoring mechanism includes a clamping member coupling to one end of the seat belt and being longitudinally displaceable on a supporting beam secured to the body of the vehicle and adapted for arresting the clamping member in the case of a collision.
Belt locking means for safety belts which are not provided in most vehicles include a locking buckle which is adapted for receiving a locking belt plug and which is mounted in a holder, the latter being fixedly attached to the floor of the vehicle. The conventional belt locks which are fixed to the floor of the vehicle maintain their fixed position irrespective of the actual position adjustment of the vehicle seat which apart from the longitudinal position adjustment can also be adjusted vertically. For this reason, in the event that the vehicle seat has been vertically adjusted to its height position and displaced forwardly to its extreme longitudinal position, as the case may be when persons of smaller height use the seat, the locking part of the safety belt remains too far behind the seat and the insertion of the plug into the socket becomes difficult. To avoid this shortcoming, an anchoring mechanism for the seat belt has been developed in which the portion of the seat belt which carries the socket buckle is maintained in a fixed position relative to the vehicle seat irrespective of the adjustment of the latter. In this known construction of the anchoring mechanism the socket buckle of the belt is connected to a clamping member which is shaped as an angular lever and pivotably mounted on the seat. The clamping member has a fork-like guiding portion which engages the supporting beam, the latter being also pivotably mounted on the vehicle body. This supporting beam or rail has on its lower side an arresting rack provided with a lining, the rack in the case of a collision being engageable with an arresting tooth of the clamping member which penetrates the soft, preferably plastic lining of the rack. The pivot point of the socket buckle on the belt and the pivot point of the locking or arresting booth form respectively, end points of the clamping member that is pivotably supported on the seat. The arresting tooth of the clamping member has the form of a bolt which normally slidably rests on the supporting beam when the plug of the safety belt is introduced into a guiding notch of the clamping member. During the position adjustment of the seat the clamping member is displaced on the supporting beam which, according to the position of the seat, is slightly inclined upwardly or downwardly. In this manner the buckle of the belt remains always in the same position relative to the vehicle seat.
In the buckled condition of the seat belt there is still the possibility that during the longitudinal displacement of the vehicle seat in forward direction the clamping member may become locked, particularly when the belt winder is blocked and does not permit unwinding of the seat belt. Moreover, in the case of a collision, the attachment point of the belt buckle to the clamping member moves in a certain range forwardly, this forward movement being caused by the swinging movement of the clamping member on the one hand and by the swinging movement of the supporting beam on the other hand so that the safety belt loop is increased and so increases the danger of injury of the user of the safety belt.